Lubricants containing salts of organicsubstituted phosphonic acid



United States PatentO LUBRICANTS CONTAINING SALTS OF ORGANIC- SUBSTITUTED 'PHOSPHONIC ACID Arnold J. Morway, Clark, Jeffrey H. Bartlett, New Providence, and Clifford W. Muessig, Colonia, N.J., assignors to Esso Research and Engineering Company, a corporation of Delaware No Drawing. Filed Apr. 25, 1957, Ser. No. 655,001

8 Claims. (Cl. 252-325) This invention relates to lubricating compositions containing salts of hydroxy alkyl or alkenyl phosphonic acids. Particularly, it relates to greases and lubricating fluids containing complexes of salts of carboxylic acids and salts of l-hydroxy alkyl or alkenyl phosphonic acid wherein said alkyl or alkenyl group contains 10 to 30 carbon atoms.

Mixed-salt complexes of salts of low molecular weight carboxylic or fatty acid, in combination with salts of intermediate and/or high molecular Weight fatty acids, are known. These prior complexes have been used as grease thickeners arid for imparting certain desirable properties to fluid-type lubricants. However, it has now been found that greases and lubricating fluids may be prepared from complexes of salts of high molecular weight hydroxy alkyl or alkenyl phosphonic acid in various combinations with salts of low molecular weight carboxylic-acids, intermediate and high molecular weight carboxylic acids. This new typeof complex may be incorporated in lubricating oil in amounts of to 30 weight per cent, based on the total composition, to form greases having higher load-carrying ability and a lower degree of thixotropy than greases thickened with the aforementioned prior complexes. Suchlow thixotropic greases are very plastic and are particularly useful in centralized lubrication systems because of their ease of pumping and their good slumping properties. I Yet, be: cause of their extreme plasticity, relatively large amounts ice known to the art. Examples of specific compounds which may be used include:

Suitable low molecular weight acids used in forming the complex, include saturated and unsaturated, substituted and unsubstituted aliphatic monoand polycarboxylic acids having about 1 to 6 carbon atoms. These acids include fatty acids such as formic, acetic, propionic, furoic, acrylic, adipic and similar acids including their hydroxy derivatives such as lactic acid, etc. Formic and particularly acetic acids are preferred. Mixtures of these low molecular weight acids may be employed if desired.

Intermediate molecular weight fatty acids operable for the complex formation include those aliphatic, saturated or unsaturated, unsubstituted, mono-carboxylic acids I containing 7 to 12 carbon atoms per molecule, e.g.,

of the thickener can be incorporated into the grease so as to increase the extreme pressure properties of the grease Without undue hardening. By using smaller amounts, such as 5 to 20 weight percent, of the complex of the invention, fluid lubricants may be formed also having high load-carrying ability and reduced wear properties.

The high molecular weight hydroxy alkyl or alkenyl phosphonic acid utilized in the present invention has the general formula:

wherein R is an aliphatic hydrocarbon radical, which may be saturated or unsaturated, and either straight or branched-chain, i.e. alkyl or alkenyl radicals, said R containing about 1 to 30, preferably 10 to 20, carbon atoms. R may be either hydrogen or an aliphatic hydrocarbon radical, saturated or unsaturated, straight or branched-chain, i.e. alkyl and alkenyl radicals containing about 1 to 20, preferably 1 to 10, carbon atoms. However, the total number of carbon atoms in the molecule should be about 11 to 31, e.g. 15 tov 24. Compounds ofthe-above types and methods for their preparation are capric, caprylic, nonanoic, lauric acids, etc.

The high molecular weight fatty acids or aliphatic monocarboxylic acids useful for forming the complexes of the invention include naturally-occurring or synthetic, substituted and unsubstituted, saturated and unsaturated, mixed or unmixed fatty acids having about 16 to 30, e.g. 16 to 22, carbon atoms per molecule. Examples of such acids include palmitic, stearic, hydroxy stearic such as: 12-hydroxy stearic, di-hydroxy stearic, poly-hydroxy stearic and other saturated hydroxy fatty acids; behenic, montanic, arachidic, ricinoleic, linolinic, linoleic, oleic,

hydrogenated fish oil, tallow acids, etc.

The metal component of the complex thickeners of this invention may be either an alkali metal such as lithium, potassium, sodium or an alkaline earth metal such as calcium, strontium, barium and magnesium. Mixtures of the grease-forming metals may be employed if desired. The metals are usually reacted with the acids in the form of metal bases, such as hydroxides, oxides, carbonates, etc.

The compositions of the invention will comprise a major proportion of a lubricating oil and about 5 to 30 weight percent of the complex material. When a grease is desired, the composition will contain about 15 to 30, e.g. 20 to 30 weight percent of the complex, while in the case of fluid lubricants, the composition will contain about 5 to 20, e.g. 5 to 15 weight percent of the complex.

The thickener, in turn, will contain the salts'of about 1 to 5, e.g. 1 to 3, moles of the high and/or intermediate; molecular weight fatty acid per mole of the phosphonic acid. If the salt of a low molecular weight fatty acid is also used in the preparation of the complex, then it will be present in ratios of about 1:1 to 30: 1', e.g. 52-1 to 25:1 moles of the low molecular weight fatty acid salt per mole of the phosphonic acid salt. In terms of parts by weight, excellent mixed-salt thickeners may be prepared from a any proportion; about 0 to15,e.g. 4 to12 parts by weight of low molecular weight fatty acid; and sutficient metal base to neutralize said mixture of acids.

Various other additives may also be added to the lubricating composition (e.g. 0.1 to 10.0 weight percent acetic acid and 3.0 weight percent of 1-hydroxy-1-methylhexadecyl phosphonic acid was then added to the limeoil dispersion and stirred in for A hour. The mixture was heated to 460 F. for about /2 hour, then allowed based on the total weight ofnthe composition), for exam- 5 to cool to 200 F. Then 1.0 weight percent phenyl ple, detergents such as calcium petroleum sulfonate; a naphthylamine was added. The grease was further oxidation inhibitors such-as phenyl alpha naphthylamine; cooled to 150 F. and then passed through a Gaulln viscosity index improvers such as polyisobutylene; corhomogemzer. rosion inhibitors such as sorbitan monooleate; pour dem Lubricant A pressams; dyes; other i f g g a f' b A grease was prepared in a manner similar to that In general the comppsnions t e m e of Example I but having the composition noted in Table prepared by coneutrallzatlon of the fatty acid and I which follows phosphonic acid in situ in a lubricating oil menstruum Lubricant B by the addition of a metal base, followed by heating to 15 a temperature and for a time sufficient to form the com- A grease was Prepared a manner l f plex. Generally, the mixture will be heated to about f l i i g g f z gi Composmon 400 to 700 1=., e.g. about 430 to 600 F. The tem- Q g f g an 522 3; perature may then immediately be allowed to drop, but g g preferably is maintained for about /2 to 4 hours in order Lubricant C to ensure completion of the complex formation. The A fl id lubricant was f d by mixing 5 Weight mlxtlll'e may be fi about 150 to 200 Pa percent of Lubricant B with 62.5 weight percent of a where conventwnal additives, If y y be addede mineral lubricating oil of 80 S.S.U. viscosity at 210 F. mixture may then be homogenized Such as by pa mg The compositions and properties of the above lubrithrough a Gaulin homogenizer or 21 Charlotte mill, 01- cants are given in Table I.

TABLE I Lubricant Lubricant Lubricant I A B c Formulation (Weight Percent):

Glacial Acetic Acid 12. 00 12.0 15. 0. 4. 40. Caprylic Acid 1.7 Capl'ic Avid. 1.25. Wecnline AAC Acid 6. 3. 1.18. C Phosphonic Acid. 3. Hydrated Lime 9.50 9. 11. 3.30. Phony] a Naphthylamine 1.00 1.0 0. 5 0.13. Mineral Oil (55 SUS at 210 F.). 71. 0 71.2 Mineral Oil (F0 SUS at 210 F.).. 09.4 .03. Mole Rati of intermediate Moi. Wt. Fatty Acid to Phosphonie Acid, 2. ll Mole Ratio of Acetic to Phosphonic Acid 22.4/1

Properties:

Appearance Fluid, Solid. Solid, Fluid.

uniform uniform soft product. grease grease. Dropping Point, F.- 500+ Con=islency- Penetrations. 77 F., mm./10:

Un worked..- 340 Worked, m Strokes am am Worked, 100,000 strokes" 325 im Visc sity S.S.U.

100 F 2. tin 2,054. 210F 2 102. Extreme Pressure Properties- Almen Test:

Gradual Loading- Wgts Carr 1K 8. Pin Condition Fxr-ellent Fxoeilpnt Exccllent Shem-ed, Shock Lnading- Wgts. Carrie 15 1H 15 Pin Condi Fw'eient Exeellent.... Excellent... Timken Test:

lbs. load Pass Pass Pass 4 Ball Wear Test,-Scar Spot Diru, mm.-

(1,800 r.p.m.10 Kg .lH0ur-75C.)-- 0.20 0.24 0.23 0.20.

1 Wee line AAC acid is a mixture of: 28 weight percent Caprylic, 56 weight percent capric, and 16 weight percent iauric acids.

lowing examples which include the preferred embodi-'- ments of the invention.

1 EXAMPLE I A fluid lubricant was prepared as follows: 9.5 weight percent of hydrated lime was dispersed in 71.5 weight.

percent of a mineral lubricating oil having a viscosity of S.S.U. at 210 F. 1.75 weight percent caprylic acid,

As seen from the preceding table, by using the phosphonic acid of the invention in place of a portion of the intermediate molecular weight fatty acid (compare Example I and Lubricant A) a fluid lubricant is ob- Even when the propor-' tained rather than a solid grease. tions of the intermediate molecular weight fatty acid is reduced and the proportion of acetic acid is increased as in Lubricant B, still a solid grease is formed. These (compositions illustrate the fiuidizing effect of the high molecular weight phosphonic acid when incorporated into complex type thickeners. It is also ,to be noted that the fluid lubricant of the invention had extreme pressure properties comparable to those of the solid greases. When 1. 25 weight percent ofcapric acid, 12.0 weight percentit was attempted, as in Lubricant C, to cut back Grease B, with additional mineral oil to form a fluid lubricantof the comparable viscosity to the fluid of the invention, the extreme. pressure properties were greatly reduced. In the past, 'it was common practice to try to increase the extreme pressure properties of fluid lubricants by increasing their thickener content so as to obtain a larger proportion of metal in the lubricant. However, the drawback to this method was that by increasing the soap content so as to obtain the desired extreme pressure properties, the fluids became unduly heavy or viscous. However, by using the complex material of the invention, fluid lubricants may be obtained which will have a high proportion of metal content and yet still be extremely fluid.

It has been known to form complex thickeners comprising salts of a high molecular weight fatty acid and salts of acrylic acid by heating whole fat such as tallow, hog fat,-lard oil, fish oil, or vegetable oils such as rapeseed oil, mustard seed oil, etc., to a high temperature in the presence of a large excess of alkali, such as sodium or potassium alkali. The fat becomes saponified at about 350 F., then upon further heating to about 500 F., a portion of the fat breaks down to form glycerine which is dehydrated to acrolein which, in turn, is converted into salts of acrylic acid. However, the large excess of alkali necessary for such reactions tends to make the grease more abrasive and therefore undesirable from a dermatitis standpoint. It has now been found that by neutralizing the excess alkali with the high molecular weight phosphonic acid of the invention, that the extreme pressure and antiwear properties of the grease are much improved, while the abrasiveness due to the excess alkali is eliminated.

Greases of the above type are readily prepared by dispersing a fat in lubricating oil, adding about -1.5 to 3.0 time's'the amount of alkali necessary for saponification, heating to a temperature of about 450 to 650 F., e.g. 500 to 550 F., for about to 30 minutes, or until foaming due to hydrogen evolution ceases. The mixture may then be cooled, say to about 200 to 400 F., e.g. 250 to 300 R, where sufiicient phosphonic acid is added to neutralize any excess alkali, then maintaining a temperature of about 250 to 300 F. for about to 45 minutes in order to ensure the complete reaction of the phosphonic acid with the excess alkali, followed by cooling to room temperature.

This concept of the invention is illustrated by the following examples.

EXAMPLE II-A A grease was prepared by charging mustard seed oil, mineral oil and sodium petroleum sulfonate (average molecular weight of 450) to a kettle and warming to 150 F. while mixing. A 40 percent aqueous solution of sodium hydroxide was added to the kettle and the contents were further heated. Dehydration and foaming then occurred, which ceased at temperatures of about 350 P. On continued heating to 450 F., foaming again began. Heating was continued to 520 F. and the temperature maintained there for about minutes, until foaming ceased. Heating was discontinued and the temperature was allowed to drop to 300 F., at which point the hydroxy phosphonic acid was added. The mixture was maintained at 300 F. for about 30 minutes. Then phenyl alpha naphthylamine was added and the grease cooled to 150 P. where it was passed through a Gaulin homogenizer operating at 6,000 p.s.i. The grease was then cooled to room temperature.

EXAMPLE II-B A grease similar to that of Example II was prepared, except that the excess alkalinity was not neutralized with the phosphonic acid.

The compositions of the above greases and their physical properties are shown in Table II.

Penetration, 77 F., mm./l0

Unworked Worked, 60 strokes- Worked, 100,000 stroke Lubrication Test I (204 Bearing 10,000 r.p.m.)-- 30 min Time and Temperature Rise 75 F 75 F 4 Ball Wear Test Spot Diam., mm. (1,800 0.45 0.65.

r.p.m.-10 Kg. Ld.1 hour-75 0.). Color Stability-2 weeks at 250 F Good Pztgorfi Normal Hoflmann Oxidation+Hours to 5 i 2 p.s.i. Drop.

Anti-Friction Bearing Manufacturers AssociationNational Lubrieating Grease Institute Cooperative Test for Lubrication Life.

2 Slight darkening, no crust formation.

3 Dark, slight crust formation.

As seen from the above table, excellent solid greases may be prepared wherein the thickener comprises mixed salts of high molecular weight fatty acid, a low molecular weight fatty acid and the high molecular weight phosphonic acid. Furthermore, the incorporation of the phosphonic acid into the complex forms greaseshaving improved wear and color stability properties (compare II-A with II-B).

What is claimed is:

1. A lubricant composition comprising mineral lubricating oil in a major proportion and about 5 to 3 wt. percent of a mixed-salt complex comprising metal salt of fatty acids selected from the group consisting of intermediate and high molecular weight fatty acids and metal salt of a phosphonic acid having the formula:

OH O

wherein R and R are selected from the group consisting of hydrogen and aliphatic hydrocarbon radicals, the total number of carbon atoms in the molecule are 11 to 31, and wherein the molar ratio of said fatty acid to said phosphonic acid is about 1 to 5 moles of fatty acid per mole of phosphonic acid and wherein said metal is selected from the group consisting of alkali metals and alkaline earth metals.

2. A lubricant composition according to claim 1, wherein said fatty acids comprise a mixture of C7 to C fatty acids. i

3. A lubricant composition according to claim 1, wherein said mixed-salt complex include salts of a C to C fatty acid, in a molar ratio of said C to C fatty acid to said phosphonic acid of about 1:1 to 30:1.

4. A lubricant composition consisting essentially of a I A major amount of mineral lubricating oil and about 5 to 30 weight percent, based on the total composition, of a thickener comprising in a molar ratio: metal salt of about 1 to 30 moles of C to C fatty acid, metal salt of about 1 to 5 moles of C to C fatty acid and metal salt of 1 mole of l-hydroxy alkyl phosphonic acid contain ing 11 to 31 carbon atoms, and wherein said metal is selected from the group consisting of alkali and alkaline earth metals. j

5. A method of preparing a lubricant composition comprising a major amount of mineral lubricating oil'and about 5 to 30 wt. percent of a mixed-salt material which comprises heating to temperature of about 400 to 700 F. a mineral lubricating oil dispersion of a neutralized mixture of: 0.5 to 5 parts of phosphonic acid having the general formula wherein R and R are selected from the group consisting of hydrogen and aliphatic hydrocarbon radicals, the total number of carbon atoms in the molecule are 11 to 31; l to 25 parts of fatty acid selected from the group consisting of C to C fatty acid and C to C fatty acid and mixtures thereof; to 15 parts of C to C fatty acid; said acid mixture being neutralized with a base selected from the group consisting of alkaline earth metal bases and alkali metal bases.

6. A process for the preparation of a lubricant composition consisting essentially of a major amount of mineral lubricating oil and about to 30 wt. percent of mixed salts of fatty acid and phosphonic acid, which comprises coneutralizing with a metal base a mineral lubricating oil dispersion of fatty acid and phosphonic acid having the general formula:

wherein R and R are selected from the group consisting of hydrogen and aliphatic hydrocarbon radicals, the total number of carbon atoms in the molecule are 11 to 31, heating the neutralized mixture to a temperature of about 400 to 700 F. to form said complex, and then cooling, said metal base being selected from the group consisting of alkali metal bases and alkaline earth metal bases.

7. A process for the preparation of a lubricant composition consisting essentially of a major proportion of mineral lubricating oil and about 5 to 30 wt. percent of mixed salts of fatty acid and phosphonic acid, which comprises reacting a dispersion of whole fat in mineral lubricating oil with about 1.5 to 3.0 times the amount of alkali needed for complete saponification of said fat, at temperatures of about 450 to 650 F. until hydrogen evolution ceases, then neutralizing said excess alkali with a phosphonic acid having the formula: on o wherein R and R are selected from the group consisting of hydrogen and aliphatic hydrocarbon radicals, the total number of carbon atoms in the molecule are 11 to 31, then cooling to form said grease.

8. A lubricant composition prepared according to the method of claim 7 wherein said alkali is sodium hydroxide and the amount of whole fat is sufficient to form a grease thickening amount of the complex thickener.

UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent N0; 2,977,303 March 28, 1961 I Arnold Ja Morway et al..

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

a Column 6 line 39 for "about 5 to 3 wt." read about 5 to 30 wt.

Signed and sealed this 22nd day 0? August 1961.,

I (SEAL) Attest:

ERNEST w. SWIDER DAVID L. MD

Attesting Officer Commissioner of Patents 

1. A LUBRICANT COMPOSITION COMPRISING MINERAL LUBRICATING OIL IN A MAJOR PROPORTION AND ABOUT 5 TO 3 WT. PERCENT OF A MIXED-SALT COMPLEX COMPRISING METAL SALT OF FATTY ACIDS SELECTED FROM THE GROUP CONSISTING OF INTERMEDIATE AND HIGH MOLECULAR WEIGHT FATTY ACIDS AND METAL SALT OF A PHOSPHONIC ACID HAVING THE FORMULA: 